In order to meet the development requirements of multimedia communication services, high order modulation such as multiple quadrature amplitude modulation (Multiple Quadrature Amplitude Modulation, MQAM) is widely used in a modern wireless communication system, so as to provide a higher information transmission rate in a limited frequency band. However, the high order modulation is very sensitive to factors such as phase noise and Gaussian noise in a signal transmission process, the noise enables a receive signal of a receiving end to randomly move or rotate when compared with a correct corresponding modulation constellation point, so that a decision of the receiving end on a transmit signal corresponding to the receive signal is affected, and a wrong modulation constellation point and a corresponding data bit may be demodulated.
In the prior art, during demodulation processing, only an impact of Gaussian noise on a receive signal is considered in some demodulation methods without considering an impact of phase noise; however, with a modulation order adopted in the wireless communication system becoming increasingly higher, the density of constellation points increases, and an impact of the phase noise on the demodulation is increasingly remarkable, and if the phase noise is not considered, it may lead to a wrong demodulation result. Alternatively, although both the Gaussian noise and the phase noise are considered in some demodulation methods, the existing demodulation algorithm has a low anti-phase-noise capability, and when the phase noise is large, the impact of the phase noise on a demodulation result is still remarkable.